If by call tones, you mean ring tones, then yes, you certainly can. There's a number of ways to get ring tones. Some folks make their own, using .mp3's. I get a lot of mine from
www.phonezoo.com. It's user maintained, so there's no licensing issues. It's also free. Anyway, once you d/l the tones you want, make sure they are in the My Documents folder. Go to Sounds and Notifications, click the Notifications tab, and then select Event from the drop down. Next, select the ringtone you want for that event from the Play Sound drop down.
Do understand that this is the procedure I follow for my Treo 700WX, the procedure for your 800W may be somewhat different.